Wireless broadcasting is well known for television and radio content. As used herein, “broadcasting” means simultaneously sending the same content to multiple recipients. A distinction is sometimes made between broadcasting and multicasting, wherein broadcasting sends the content to everyone on a network, whereas multicasting sends content to a select list of recipients. As used herein, “broadcasting” is used generically to mean simultaneously sending the same content to all or a subset of all wireless terminals on a network.
Satellite broadcasting is widely used for multimedia (audio and/or video) content. For example, Direct Broadcast Satellite (DBS) systems, such as marketed by DirecTV and/or EchoStar, broadcast television content to fixed and/or mobile terminals. Satellite radio systems, such as marketed by XM-Satellite Radio and Sirius Satellite Radio, broadcast audio to fixed and/or mobile terminals.
Broadcasting of high bandwidth multimedia (video as well as audio) content to relatively low gain portable wireless terminals may present a challenge. In particular, high bandwidth streaming media, such as video and/or high fidelity audio over satellite, may present particular challenges. More specifically, in wide area broadcasting, it is desirable for adequate power flux density to be provided by the satellite over the entirety of a targeted coverage area. Such an area might be, for example, substantially all of the United States and Southern Canada. When the coverage area is large, as in the above example, the satellite antenna gain generally is relatively small, as the antenna gain generally is inversely proportional to the coverage area that it must span. However, high bandwidth content generally requires/uses high power because it generally provides transmission at a high information rate. Thus, the broadcast of such content over a large area may use a relatively high level of aggregate effective isotropic radiated power, or AEIRP, in the satellite. This tends to make the satellite complex and expensive.
Conventionally, dedicated broadcast satellites have used relatively low gain antennas coupled to relatively high gain Power Amplifiers (PAs). Even then, it may be difficult to provide video broadcast to user terminals with low antenna gain, such as cellular/PCS terminals, over large coverage areas, although trials involving direct satellite broadcast to hand held devices over relatively small geographic areas have been conducted. FIG. 1 shows an example of a satellite coverage map for a single-beam broadcast satellite covering a geographic area of the USA and Southern Canada.
As used herein, the term “user terminal” includes terrestrial cellular and/or satellite cellular radioterminals with or without a multi-line display; terminals that may combine a radioterminal with data processing, facsimile and/or data communications capabilities; Personal Digital Assistants (PDA) that can include a radio frequency transceiver and/or a pager, Internet/Intranet access, Web browser, organizer, calendar and/or a global positioning system (GPS) and/or GLONASS receiver; and/or conventional laptop and/or palmtop computers or other appliances, which include a radio frequency transceiver. As used herein, the term “user terminal” also includes any other wireless user device that may have time-varying or fixed geographic coordinates, and may be portable, transportable, installed in a vehicle (aeronautical, maritime, or land-based), or situated and/or configured to operate locally and/or in a distributed fashion at any other location(s) on earth and/or in space. A user terminal also may be referred to herein as a “cellular radiotelephone,” “cellular terminal”, “radiotelephone”, “wireless terminal” or simply as a “terminal.”